Eosinophils are associated with many allergic diseases including asthma, atopic dermatitis, drug reactions and chronic urticaria. The myriad of eosinophil related diseases has led us to investigate the development of eosinophils from hematopoietic stem cells in an attempt to understand the signals prompting eosinophil production in the bone marrow. Gene profiling of developing eosinophils has shown that a novel hypothetical protein is expressed as mRNA. TMEM103 mRNA is expressed in IL-5 stimulated CD34+ cells, bone marrow and in mature eosinophils. The transcript, TMEM103, has been shown to be associated with ribosomes and the protein has been identified by western blot analysis in developing eosinophils. This grant proposes to further verify the existence of TMEM103 by raising monoclonal antibodies to the protein, then purifying and sequencing the protein. Further, the function of TMEM103 will be investigated by RNA silencing followed by studies investigating morphological and transcription profile changes. PUBLIC HEALTH RELEVANCE: Eosinophils are leukocytes associated with asthma and allergic diseases. This project explores the role of TMEM103, a novel protein, in eosinophils.